Competition for Nest Sites between Sand Martins and Coots

Walking along Kennetside this morning, I saw a couple of sand martins (Riparia riparia) flying up and down the river.  This itself is unusual because I cannot remember having seen sand martins before, certainly not since I moved down south in 1988.  Hence I was quite surprised to see them in central Reading. 

On the north side of that part of the river there are several rainwater run-off pipes that stick out from the bank.  At one point, one of the martins swooped down to the mouth of a pipe, but a nearby coot (Fulica atra) raised it head as if surprised, and the martin flew up and away.  Then a few seconds later the sand martin came down again and, this time manage to perch at the entrance of the pipe.  However, when the coot saw this, it flew up, scaring the sand martin away, and  then stood itself in the entrance to the pipe, as if standing guard.  The martins then flew off up the river and, after a little while, the coot flew back down to the water and continued with what it had been doing before the interruption.

I have noticed coots trying to nest in those pipes before, but I don't think any can have succeeded because in heavy rain the flow of water from the pipes is so great that it would easily wash out any nest material.

Update on Fri 2009-06-12 by Tristram Brelstaff

The sand martins are more persistent than I thought.  On two occasions since then I have seen them going in and out of the same pipes, and the coot was nowhere to be seen.

The Destroyer of Insects

A dead dung fly, probably Scathophaga stercoraria, infected with a fungus, probably a member of the genus Entomophthora (Ento = insect, mophthora = destroyer).  Apparently, before these fungi kill their hosts, they make them move to the tip of a blade of grass or twig and stand there with their wings in the open position.  Presumably this improves the dispersion of the spores that eventually emerge from the dead body.

Photos taken in Reading University grounds, Reading, UK, on 2009-05-29.

Hoverfly

Tentative identification Eristalis horticola (also known as Eristalis lineata), based mainly on comparison with photos here and here.

Photos taken in Reading University grounds, Reading, UK, on 2009-05-31.

Bumble-bee Mimic

Hovefly Volucella bombylans, the most convincing bumble-bee mimic I have yet come across.

Photos taken in Reading University grounds, Reading, UK, on 2009-05-31.

Ichneumon Wasp

An ichneumon wasp (order Hymenoptera, family Ichneumonidae).  These wasps are all parasitic: they lay their eggs in the larvae of other insects (mostly butterflies or moths) and when the eggs hatch out the young proceed to eat the host from the inside out.

When taking the above photo, I thought that the wasp was interested in the flowers. It was only later that I noticed that there was a caterpillar hidden in the flower head. 

The wasp flew off a little way and landed near another caterpillar.  As it approached this second caterpillar, it curved its tail under its body, as if it was going to lay an egg in it, but got disturbed by a gust of wind and flew off again.

I haven't attempted to identify the wasp; there are about 3,200 species of ichneumon wasp found in the British Isles and identifying them properly is a non-trivial exercise.  The caterpillars might be the larvae of the blossom underwing moth (Orthosia miniosa), though I am not entirely sure of that. [Note added 2009-06-07: I now think that the caterpillars are Depressaria daucella.]

Photos taken in Reading University grounds, Reading, UK, on 2009-05-29.